1. Field of the Invention
This invention relates to a method and apparatus for measuring gas flow from a test cell of the type used to analyze decomposition and gas formation to be expected from sanitary land fills containing municipal solid waste material. In such test cells, the period of time for measurement is several years and the production rate of gas may vary widely. In such test cells, the rate of gas production may at times be very low. Still further, it is necessary in such test cells to prevent any ambient air from entering the test cell during the measurement period because contamination of the gas within the cell will destroy the accurate measurement of the gas produced in the test cell.
2. Description of the Prior Art
In systems used heretofore, it has been difficult to measure the gas flow rates when the flow becomes very low because of changing temperature conditions, barometric pressure, or decreased gas production which is experienced after several years have passed during a test period.
Without an accurate automated gas monitoring system to determine the gas output from a test cell, it has been impossible to obtain consistent and accurate gas output measurements from such cells.
Gas generation in sanitary land fills creates two major problems which affect the environment. Carbon dioxide is produced by the land fill and goes into solution in the surrounding ground water and causes a "hardness halo" in the ground water near the fill. Still further, methane gas is produced, and this gas can migrate off site and create harzardous conditions in surrounding structures. Therefore, it has been necessary to accurately investigate the gas production quantity and constituency of sanitary land fills which contain municipal solid waste matter. Test cells which simulate the land fill have been built in order to obtain a more accurate measurement of composition and amount of gas produced during decomposition. It is therefore essential that accurate measurement of the gases produced by such test cells be made, in order to fully understand the pollution problem, and to further exploit the possible fuel source available from the methane gas production from such land fills.
It is this demand for accuracy which has led to the development of the invention disclosed and described herein.